Internal valves are used in a variety of commercial and industrial applications to control fluid flow between a fluid storage container and another container, hose, pipeline, etc. Typically, internal valves are provided with a bonnet assembly that includes a shaft coupled to a cam that rotatably engages a stem to open and close the internal valve.
Bonnet assemblies of known internal valves include a spring that exerts a force on a valve packing to urge the valve packing against a portion of the shaft. The engagement between the valve packing and the shaft creates a substantially bubble tight seal to prevent fluid from exiting through the bonnet assembly. In time, the resilience of the valve packing and the amount of force that the spring exerts on the valve packing decrease, which may enable fluid to exit through the bonnet assembly between the shaft and the valve packing.
In some instances, the fluid storage container in which the internal valve is mounted is located in a rural location in which repair technicians and/or replacement parts are not readily available. As a result, if a bubble tight seal does not exist between the shaft and the valve packing, the internal valve may be inoperable and/or a considerable amount of fluid may exit through the bonnet assembly before the internal valve is repaired and/or replaced.